This invention relates to fiber reinforced composite shafts and, more especially, to vehicle drive shafts comprising a fiber reinforced resinous shaft body with metallic coupling sleeves mounted at the ends thereof.
Tubular fiber reinforced composites have been heretofore proposed, as demonstrated by U.S. Pat. Nos. 2,882,072 issued to Noland on Apr. 14, 1959, and 3,661,670 issued to Pierpont on May 9, 1972. In the Pierpont patent, for example, it has been proposed to form such composites from a resinous material which is reinforced by glass fibers. In particular, filaments bearing a non-hardened resinous material (i.e., an uncured thermosetting resin) are wound around a mandrel until the desired thickness has been established. The reinforcing fibers can be positioned within the wall of the tubular composite in varying angular relationships. Thereafter, the resinous material is solidified (i.e. is cured). A premolded threaded end portion can be mounted at the ends of the tubular composite, such as by the winding of filaments directly around the end portion during the winding process.
It recently has been proposed to form vehicle drive shafts from tubular fiber reinforced composites, as demonstrated by U.S. Pat. No. 4,041,599 issued to Smith on Aug. 16, 1977, and published Japanese Application No. 52-127542, entitled "Carbon Fiber Drive Shaft" which claims priority for the filing of U.S. Ser. No. 676,856 on Apr. 14, 1976 of Gordon Peter Morgan now U.S. Pat. No. 4,089,190. In the Japanese application filaments bearing a non-hardened resinous material (e.g., an uncured thermosetting resin) are wound around a mandrel until the desired thickness has been established, whereupon the resinous material is cured. Zones or layers are positioned circumferentially within the wall of the shaft in the specific angular relationships there disclosed.
The above-mentioned Smith patent proposes the attachment of a carbon fiber reinforced epoxy drive shaft directly to a universal joint extension by a specific bonding technique.
Fiber reinforced composite shafts exhibit advantages over metallic shafts, i.e., they are lighter in weight, more resistant to corrosion, stronger, and more inert.
In copending application Ser. No. 890,232 filed concurrently herewith, of Derek N. Yates and David B. Rezin entitled "Improved Carbon Fiber Reinforced Composite Drive Shaft," now U.S. Pat. No. 4,171,626 a fiber reinforced composite drive shaft is disclosed which exhibits improved service characteristics and the necessary strength and durability to withstand the various stresses encountered during vehicle operation. The disclosure of that copending application is herein incorporated by reference as if set forth at length.
Since direct welding or bonding of a resin shaft to metal does not normally create a sufficiently strong and durable connection on a consistent and reliable basis, the use of metallic connector sleeves mounted at the ends of the shaft in accordance with the concept of the present invention provides a means for accomplishing a secure welded connection similar to that utilized with conventional metallic shafts.
The high torque loads which are to be transmitted by a vehicle drive shaft require that an extremely strong and durable torsional drive connection be established between the sleeves and shaft body. Previous proposals for mounting sleeves by employing adhesives or by wrapping the filament bundles around circumferential grooves on the sleeve periphery, cannot be relied upon to provide a connection of the requisite strength and durability.
It is, therefore, an object of the present invention to provide a novel, fiber reinforced resin shaft which minimizes or obviates problems of the types discussed above.
It is an additional object of the invention to provide a novel, fiber reinforced resin shaft suitable for use as a drive shaft in a vehicle power train.
It is a further object of the invention to provide novel methods and apparatus for securing metal connector sleeves to the ends of fiber reinforced resin shafts to enable the shafts to transmit high torsional loads.